The present invention relates to an antibacterial aqueous solution comprising a phosphate, a citrate, and a silicate. The present invention is also related to a method of controlling bacterial contamination and/or growth in a food substance, a method of prohibiting the formation of, and/or facilitating the removal of, silicate aggregation on a metal substrate, and a method of, for environmental protection purposes, reducing phosphate usage in industrial antibacterial processes.
Bacteria live everywhere in our environment, air, soil, rock, and water. Many bacteria are pathogenic and can cause diseases such as Botulism food poisoning, E-coli food poisoning, Cholera, Whooping Cough, Plague, Scarlet fever, Diphtheria, Tuberculosis, Typhoid fever, Anthrax, and so on and so forth. The extent of food borne infections in the United States was quantitatively documented in the CAST report of 1994 (Foodborne Pathogens: Risks and Consequences. Task Force Report No. 122, Council for agricultural Science and Technology, Washington D.C.), and has been extensively characterized in the past few years (CDC. 1988c. 1997 Final FoodNet Surveillance report. U.S. Department of Health and Human Services, October, 1998). Many other bacteria are, although not pathogens, spoilage bacteria and are responsible for reducing the shelf life and freshness of a food substance.
Without appropriate sanitary measures, human food substances such as fruit, vegetable, and animal meat will inevitably be contaminated or degraded by bacteria. For example, the so-called “salad in a bag” products have gained great consumer acceptance as a result of their convenience of use. However, such products are susceptible to bacterial degradation as a result of cross contamination of bacteria at the surface of one or more cut pieces of vegetables contacting other cut pieces. Similarly, animals are killed and their carcasses are processed to produce food products for human consumption. Typically, the processing of such animals includes evisceration, which may contaminate the edible portion of the animal with bacteria. Furthermore, depending upon the sanitary conditions employed in processing, additional sources for contamination exist.
Moreover, poultry carry a large population of microbes on their surface as they pass into a scalder, a typical early stage processing technique. Microbes are displaced into the scald water and can redeposit on the bird as it is removed therefrom. In addition, poultry feces may be ejected into the scald water which further escalates the presence of microbes therein. Scalded birds are then defeathered in mechanical pickers, which are often set so that the skin's epidermal layer is removed. This allows microbes to more easily bind to the naked bird. Beef carcasses similarly carry microbes on their hide into a slaughter room. Because of the violent nature of hide removal, microbe containing debris can be air-born and land on the naked carcass. Unfortunately, removal of microbes from the naked carcass of poultry or beef is difficult. Accordingly, methods of removing these microbes have been investigated.
There has been extensive research conducted in the field of food hygiene to develop compositions which function as food grade anti-bacterial agents. For example, U.S. Pat. No. 5,436,017 teaches a method of inhibiting bacterial growth in meat in which sodium citrate buffered with citric acid is introduced into the meat to a sodium citrate content of 1 to 7%, and preferably about 1 to 1.3%.
WO 97/23136 teaches a bacterial decontamination method which involves treatment with a solution of low concentration alkali metal orthophosphate combined with either osmotic shock and/or lysozyme in solution and/or nisin in solution. This reference tested the combination of low concentrations of trisodium orthophosphate with lysozyme against certain bacteria on lettuce leaves or chicken skin, and the combination of low concentrations of trisodium orthophosphate with nisin against certain bacteria on chicken skin. U.S. Pat. No. 5,283,073 has disclosed a process for treating poultry carcasses with a solution containing about 4% or greater trialkali metal phosphate, to remove, reduce or retard bacterial contamination and/or growth. However, according to the disclosure, relatively undesirable high amounts of phosphates will be dumped into waste streams and eventually into the environment. Phosphates are a major source of pollution in lakes and streams, and high phosphate levels support over-production of algae and water weeds.
In an attempt to minimize, or hopefully eliminate, the use of phosphates, U.S. Patent Application 2003/0,194,475 teaches an antibacterial method for food substances, in which a phosphate solution is replaced by an aqueous solution of alkali silicate. However, silicate tends to “aggregate” into an insoluble form and binds very tightly on the surface of metal, particularly iron based metals, such as shackles and drip pans. This aggregated silicate may commonly appear as “scale”, white spot, stain, or gummy residue, all of which are difficult to remove. For purposes of this disclosure, each of these is referred to generally as scale. Scale is generally perceived as undesirable as it may provide a surface prone to bacteria/microbe infiltration.
Advantageously, the present invention provides an antibacterial aqueous solution, which can reduce certain of the aforementioned problems. More particularly, the present invention can reduce bacterial contamination and/or retard bacterial growth in a food substance; yield a waste stream containing a limited amount of phosphate compounds; and limit the formation of, and/or facilitate the removal of, silicate aggregation on metal article.